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Drawback to not using DHW priority?

I basicallly set my Buderus 2109 to not use DHW priority because it's been having issues with not starting the Space Heating circulator or sometimes the DHW circulator until I reset the boiler switch. I'm thinking I might have a sensor problem because we will run out of hot water and then DHW circ is not running even though the boiler temp is at 150. I've set the jumpers so that there is no DHW priority and that has gotten things going again, but is there any drawback to that? I plan on getting a Buderus tech out here soon.


  • hot_rod
    hot_rod Member Posts: 20,828
    No harm, the priority just helps recover the DHW load as quickly as possible. If all the heating zones call you will have a longer DHW recovery time under your current condition.

    If the boiler is sized exactly to the load, at design day conditions you may not have enough boiler power for heat zones and DHW call. That could keep the boiler running at low return temperatures for an extended period.

    Regardless getting it repaired is a good idea, it is a nice feature to have enabled..
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • 336mlk
    336mlk Member Posts: 17
    Thanks for the tip. Just curious what would be a temperature that is too low and is that not good for a boiler?